Pyrazines are one of the most important heterocycle containing nitrogen. They are widely used for agricultural, pharmaceutical, cosmetic, polymeric chemicals and functional materials. Amino and cyano groups are especially important as the substituents, because of their potentiality to convert into other functional groups and to introduce various derivatives. Therefore, pyrazines substituted with both these groups are prospective starting materials.
Since diaminomaleonitrile (abbreviated as DAMN, hereafter) and its derivatives are commonly based starting materials in technical fields, further development of simple synthetic process from DAMN to the useful pyrazines has been expected.
Pyrazine derivatives, substituted by both amino and cyano groups such as 6-amino-2,3,5-pyrazinetricarbonitrile, 5,6-diamiono-2,3-pyrazinedicarbonitrile and 3,5-diamino-2,6-pyrazinedicarbonitrile etc., have been synthesized from DAMN or its homologues as the starting materials. (J. Org. Chem., 39, 1235 (1974) and Japanese Patent Application No. Sho 63-75909).
On the other hand, the example of the 3,6-diamino-2,5-pyrazinedicarbonitrile having symmetric structure was depicted in U.S. Pat. No. 3,674,749 as the starting material for polymers. However, the compound mentioned in the specification text was quite different from the one shown in the figure. Furthermore, in the description neither of the physical properties, nor the method of preparation of these examples of use of the pyrazine carbonitrile have been confirmed.